Electrical therapy has long been used in medicine to treat pain and other conditions. For example, transcutaneous electrical nerve stimulation (TENS) systems deliver electrical energy through electrode patches placed on the surface of a patient's skin to treat pain in tissue beneath and around the location of the patches. One problem with TENS systems is that they may not provide patients with adequate pain relief.
More recently, a technique in which electrodes are placed through the patient's skin into the target tissue has been proposed. Percutaneous Neuromodulation Therapy (“PNT”) (also sometimes called Percutaneous Electrical Nerve Stimulation or “PENS”) using percutaneously placed electrodes achieves significantly better pain relief results than TENS treatments using skin surface electrodes. This therapy is described in Ghoname et al., “Percutaneous Electrical Nerve Stimulation for Low Back Pain,” JAMA 281:818–23 (1999); Ghoname et al., “The Effect of Stimulus Frequency on the Analgesic Response to Percutaneous Electrical Nerve Stimulation in Patients with Chronic Low Back Pain,” Anesth. Analg. 88:841–6 (1999); Ahmed et al,. “Percutaneous Electrical Nerve Stimulation (PENS): A Complementary Therapy for the Management of Pain Secondary to Bony Metastasis,” Clinical Journal of Pain 14:320–3 (1998); and Ahmed et al., “Percutaneous Electrical Nerve Stimulation: An Alternative to Antiviral Drugs for Herpes Zoster,” Anesth. Analg. 87:911–4 (1998). The contents of these references are incorporated herein by reference.
One method for applying percutaneous nerve stimulation is to insert acupuncture needles into the patient's skin and attach the needles to waveform generators via cables and alligator clips to deliver a percutaneous electrical current. One drawback with this method is that the electrical connections to the needle may not be sufficiently secure and reliable. Another drawback with this method is that it may be difficult to accurately position the needles. For example, if a needle is placed too close to a nerve within a nerve region it is intended to treat, the needle itself may be painful and/or the amount of electrical current necessary to provide effective therapy may be painful. Accordingly, the practitioner may need to reposition the needle to a new location. However, it may be difficult for the practitioner to accurately reposition the needle. For example, the practitioner may lose track of the needle's original position once the needle is removed. Without having the original position of the needle as a reference, the practitioner may be unable to accurately locate the new position. Furthermore, the practitioner may not be able to accurately control the angle at which the needle re-enters the skin at the new position. If the angle is different than the initial angle at which the needle entered the skin, the tip of the needle can end up at the same point it was before the repositioning process began.